Influence of bio-immobilized lime stone powder on self-healing behaviour of cementitious composites

Abstract

For preserving cementitious systems and inhibiting the ingress of chemicals via cracks and fissure, persistent repairs are inevitable. Thus, self-healing of harmful cracks and fissures, without external intervention and onerous labours emerged as a viable approach for enhancing concrete durability. Among all, bio-inspired self-healing secured imperative position in autonomous healing of cementitious system, latterly. Microbes are potentially efficient in intrinsic healing of cementitious systems due to their ability of calcite precipitation. Instigated calcite filled the void and restrained the ingress of deleterious chemicals. Bacillus subtilis was selected as self-healing microbe due to its relatively longer reported survival in high pH environment. Microbes are inducted directly through water and immobilized via immobilizer. In this study, viability of lime stone powder (LSP), as bacterial immobilizer, is explored. Self-healing ability of Bacillus subtilis was gauged in terms of mechanical strength after cracking at 3, 7 and 28 days. For inspecting the microstructure and characterization of healing field-emission scanning electron microscopy (FESEM) and energy dispersive x-ray spectroscopy (EDX) were performed at 28 days. Hence, immobilized LSP enhanced the compressive strength of cementitious system and endorsed as a potential carrier for sustaining microbes for relatively extended periods. Furthermore, LSP is an economical locally available raw material, it eventually helped in formulating sustainable, cost-effective and proficient in crack repairing cementitious system.